Clarify EditorImportPlugin.get_visible_name.
Clarify EditorImportPlugin.get_visible_name.

According to the docs at
https://docs.godotengine.org/en/stable/tutorials/plugins/editor/import_plugins.html#the-editorimportplugin-class

> The get_visible_name() method is responsible for returning the name of
> the type it imports and it will be shown to the user in the Import dock.
> You should choose this name as a continuation to "Import as", e.g.
> "Import as Silly Material"

I've verified Godot's behavior reflects this, so the code examples
should reflect this.

Also document propagating save error in EditorImportPlugin.

It seems that the suggested code ignores any error from
`ResourceSaver.save`, but I think we should return it.

pkowal1982/godot,Valentactive/godot,ZuBsPaCe/godot,akien-mga/godot,Valentactive/godot,Faless/godot,ZuBsPaCe/godot,vkbsb/godot,Zylann/godot,DmitriySalnikov/godot,pkowal1982/godot,Shockblast/godot,Zylann/godot,BastiaanOlij/godot,guilhermefelipecgs/godot,godotengine/godot,vnen/godot,akien-mga/godot,guilhermefelipecgs/godot,sanikoyes/godot,Shockblast/godot,akien-mga/godot,DmitriySalnikov/godot,akien-mga/godot,godotengine/godot,Valentactive/godot,vnen/godot,BastiaanOlij/godot,pkowal1982/godot,josempans/godot,vkbsb/godot,vkbsb/godot,sanikoyes/godot,akien-mga/godot,Valentactive/godot,sanikoyes/godot,Zylann/godot,firefly2442/godot,Shockblast/godot,sanikoyes/godot,Zylann/godot,ZuBsPaCe/godot,josempans/godot,MarianoGnu/godot,firefly2442/godot,DmitriySalnikov/godot,Shockblast/godot,akien-mga/godot,honix/godot,Faless/godot,josempans/godot,Zylann/godot,Shockblast/godot,MarianoGnu/godot,godotengine/godot,honix/godot,BastiaanOlij/godot,vnen/godot,ZuBsPaCe/godot,vnen/godot,firefly2442/godot,Zylann/godot,honix/godot,BastiaanOlij/godot,pkowal1982/godot,guilhermefelipecgs/godot,vkbsb/godot,Faless/godot,vnen/godot,sanikoyes/godot,ZuBsPaCe/godot,Valentactive/godot,BastiaanOlij/godot,Shockblast/godot,godotengine/godot,Valentactive/godot,pkowal1982/godot,honix/godot,sanikoyes/godot,josempans/godot,BastiaanOlij/godot,BastiaanOlij/godot,akien-mga/godot,pkowal1982/godot,pkowal1982/godot,firefly2442/godot,firefly2442/godot,godotengine/godot,Zylann/godot,Shockblast/godot,guilhermefelipecgs/godot,guilhermefelipecgs/godot,guilhermefelipecgs/godot,DmitriySalnikov/godot,vnen/godot,Shockblast/godot,DmitriySalnikov/godot,sanikoyes/godot,MarianoGnu/godot,MarianoGnu/godot,Faless/godot,ZuBsPaCe/godot,MarianoGnu/godot,pkowal1982/godot,Faless/godot,firefly2442/godot,josempans/godot,guilhermefelipecgs/godot,BastiaanOlij/godot,akien-mga/godot,honix/godot,ZuBsPaCe/godot,vkbsb/godot,Valentactive/godot,vkbsb/godot,firefly2442/godot,DmitriySalnikov/godot,Valentactive/godot,godotengine/godot,ZuBsPaCe/godot,MarianoGnu/godot,josempans/godot,vnen/godot,DmitriySalnikov/godot,vnen/godot,godotengine/godot,vkbsb/godot,honix/godot,godotengine/godot,josempans/godot,guilhermefelipecgs/godot,sanikoyes/godot,josempans/godot,MarianoGnu/godot,Faless/godot,vkbsb/godot,MarianoGnu/godot,Faless/godot,Zylann/godot,firefly2442/godot,Faless/godot